1. Field of Invention
The present invention relates to a dynamic damper device, particularly to a dynamic damper device disposed between a piston of a lock-up device and a turbine hub of a fluid type power transmission device. Further, the present invention relates to a lock-up device, particularly to a lock-up device for mechanically transmitting power from a front cover to a turbine hub of a fluid type power transmission device.
2. Background Information
A torque converter as a fluid type power transmission device is embedded with a lock-up device to reduce fuel consumption. The lock-up device is disposed in a space produced between a turbine and a front cover, and is configured to mechanically couple the turbine and the front cover to directly transmit a torque therebetween.
In general, the lock-up device includes a piston and a damper mechanism. The piston is pressed onto the front cover by the action of hydraulic pressure, and a torque is transmitted to the piston from the front cover. The damper mechanism includes an output-side member coupled to the turbine, and a plurality of torsion springs for elastically coupling the piston and the output-side member. Moreover, the torque transmitted to the piston is transmitted to the output-side member through the plurality of torsion springs, and is further transmitted to the turbine.
Japanese Laid-open Patent Application Publication No. JP-A-2009-293671 describes a lock-up device in which an inertia member is mounted to the output-side member to inhibit variation in engine rotation. In the lock-up device described in Japanese Laid-open Patent Application Publication No. JP-A-2009-293671, the inertia member is mounted to the output member fixed to the turbine while being rotatable relative thereto. Further, torsion springs are disposed as elastic members between the output member and the inertia member.
In the lock-up device of Japanese Laid-open Patent Application Publication No. JP-A-2009-293671, the inertia member is coupled to the output member through the torsion springs. Therefore, the inertia member and the torsion springs function as a dynamic damper, and these components attenuate variation in rotational speed of the output-side member (turbine).